Electropositivity - Meaning, Definition, Elements, Trends, FAQs

Electropositivity

Electropositivity can be defined as the tendency of metals to have an atom donate electrons and form well-charged cations. This material is primarily composed of metallic elements, particularly alkaline metals and alkaline earth metals. It is very important to note that electropositivity is opposite to electronegativity, which is a measure of atomic metals having the tendency to receive electrons and form poorly charged anions.

Therefore, light-emitting substances have very low electronegativities and very high-energy electrons have very low electropositivity (electronegative elements usually have no metals have the tendency to lose electrons to form cations, and electropositive metals substances usually do not receive electrons. electrons to form anions). The highest electropositive elements usually form ionic salts with electronegative elements. For example, sodium is a highly electropositive metal that easily provides an electron to obtain a stable electron suspension. Chlorine, on the other hand, is a highly potent element that absorbs electrons to achieve a stable octet.

Factors Affecting Electropositivity & Periodic Trends

Electropositivity depends on:

• Nature of the metal element
• Distance between nucleus and valence shell (atomic size)
• Effective nuclear charge acting on valence electrons
• Ionization potential (lower IP → higher electropositivity)

Relationship with Electronegativity:

• Electropositivity and electronegativity show opposite trends
• Increase in electronegativity → decrease in electropositivity
• Decrease in electronegativity → increase in electropositivity

Periodic Trends:

• Across a period (left → right): Electropositivity decreases
• Down a group (top → bottom): Electropositivity increases
• Top right of the periodic table: Least electropositive elements
• Bottom left of periodic table: Most electropositive elements

Metallic Character:

• Electropositivity is a key property of metals
• Higher metallic character → higher electropositivity

Examples:

• Alkali metals are highly electropositive
• Cesium (Cs) and Francium (Fr) are the most electropositive elements
• Fluorine (F), Oxygen (O), Chlorine (Cl) are least electropositive (highly electronegative)

Electropositive Elements

1. Alkali metals (Group 1)
Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs). These are the most electropositive elements.

2. Alkaline earth metals (Group 2)
Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba)

3. Other metals
Aluminium (Al), Zinc (Zn), Iron (Fe)

Electronegativity

Electronegativity is the tendency of an atom in a molecule to attract the shared pair of electrons towards itself. It is a relative property and does not have a fixed unit; instead, it is expressed on different scales such as the Pauling scale. Atoms with small atomic size, high effective nuclear charge, and high ionization energy show high electronegativity. Non-metals, especially elements on the right side of the periodic table, are highly electronegative. Understanding electronegativity helps in predicting bond type, bond polarity, and chemical reactivity,

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Some Solved Examples

Question 1: Which of the following elements is most electropositive?

A. Na
B. Mg
C. K
D. Cs

Solution:

Electropositivity increases down a group and towards the left in the periodic table.
Cesium (Cs) lies below K and Na in Group 1 and has:

• Largest atomic size
• Lowest ionization energy

Hence, the correct answer is option (D)

Question 2: Which factor mainly increases the electropositivity of an element?

A. High electronegativity
B. High ionization energy
C. Large atomic radius
D. High electron affinity

Solution:

A larger atomic radius means valence electrons are farther from the nucleus and are easily lost, increasing electropositivity.

Hence, the correct answer is option (C)

Question 3: The correct order of electropositivity is:
A. $\mathrm{Na}>\mathrm{K}>\mathrm{Cs}$
B. $\mathrm{Cs}>\mathrm{K}>\mathrm{Na}$
C. $\mathrm{K}>\mathrm{Cs}>\mathrm{Na}$
D. $\mathrm{Na}>\mathrm{Cs}>\mathrm{K}$

Solution:

In Group 1, electropositivity increases down the group due to increasing atomic size and decreasing ionization energy.

Hence, the correct answer is option (B)

Question 4: Which element is least electropositive?

A. Fluorine
B. Oxygen
C. Nitrogen
D. Chlorine

Solution:

Fluorine has:

• Smallest atomic size
• Highest electronegativity

Therefore, it has the least tendency to lose electrons, making it least electropositive.

Hence, the correct answer is option (A)

Question 5: Electropositivity is maximum for an element having:

A. High effective nuclear charge
B. High ionization energy
C. Low electronegativity
D. High electron affinity

Solution:

Electropositivity and electronegativity are opposite properties.
Lower electronegativity → easier electron loss → higher electropositivity.

Hence, the correct answer is option (C)